<html>  
  <head>
    <style>
      #notSupported {

        background-color: lightgoldenrodyellow;
        padding: 100px 50px;
        width: 50%;
        text-align: center;
        z-index: 10;
        top: 20%;
        font-size: 20px;
        height: 70px;
      }
      
    </style>
  </head>
  <body>
    <center>
      <div id="notSupported">
        Your browser is not supported.
        Please upgrade to the latest version of <a href="https://www.google.co.uk/chrome" target="_blank">Chrome</a>, <a href="https://www.mozilla.org/firefox" target="_blank">FireFox</a> or <a target="_blank" href="https://www.microsoft.com/en-gb/windows/microsoft-edge">Edge</a><br><br>
      </div>
    </center>
  </body>
</html>